Bore sighting

I have a Bushnell Elite 4200 8-32x40 put on Tikka M595 Sporter using millet high mounts.

Today I was trying bore sighting at home against a 2x2" red dot atached to the fence at 25 yards.
When I got that red dot in my bore and then try to navigate with a rings to place the cross on the same spot, there was not enough clicks. I came about 1" short to the left and low.

What I do wrong?
In my little manual from Bushnell is says to shimm mount base, but how, can you help me, please.

Since you used all your windage that means your scope rings are not aligned with the bore, take a 3' dowel and try to align with the barrel to the best of your abilities, as for shimming, you can take a coke can and make shims, or can buy them from a hardware store, and place under rear base, then you need to lap the rings, or you can just buy a set of burris signature rings for $25 and a set of inserts $7.
Good Shootin,
Brian

Bore sight on a small(er) object further away. I use tree trunks, top of fence posts, anything that's stationary and a long distance away. You're trying to remove an angular error and the greater diatance and smaller object helps. Once you're sure you got it bore sighted, remember that you need some "up" in the bore sight to allow the bullet to "fall" into the target. I usually adjust to place the cross hairs "just a tad" below the object I've chosen as the "bore-sight" target.